Music Sales MeasurementNielsen compiles data from more than 39,000 retail outlets globally, to help record labels, publishers, artists, artist management and performance rights

NielsenSoundScan - Wikipedia, the free encyclopediaNielsenSoundScan is an information and sales tracking system created by Mike Fine and Mike Shalett. SoundScan is a method of tracking sales of music and music video products throughout the United States and Canada.